Process and apparatus for improving the heat distribution in a top and under fired horizontal coke oven battery



Oct. 2, 1962 P. FORLITI 3,056,732

PROCESS AND APPARATUS FOR IMPROVING THE HEAT DISTRIBUTION IN A TOP AND UNDER FIRED HORIZONTAL COKE OVEN BATTERY Filed Jan. 28, 1953 4 Sheets-Sheet 2 I o Q) 'T INVENTOR. PHUL FOELITI.

Y B w w,

Oct. 2, 1962 P. FORLlTl 3,056,732

PROCESS AND APPARATUS FOR IMPROVING THE HEAT DISTRIBUTION IN TOP AND UNDER FIRED HORIZONTAL COKE OVEN BATTERY Filed Jan. 28, 1953 4 Sheets-Sheet 4 M' J O t IN VEN TOR. Raul FoeLITI.

&Jau 4. 0 M

bis

ATTOPA/: r'

United States Patent Ofice 3,056,732 Patented Oct. 2, 1962 PROCESS AND APPARATUS FOR IMPROWNG THE HEAT DTSTRIBUTHON liN A TOP AND UNDER amar) HORIZONTAL COKE OVEN BATTERY Paul Forliti, St. Paul, Minn., assignor to Koppers Company, Inc., a corporaton of Delaware Filed .lan. 28, 1953, Ser. No. %3,647 4 Clairns. (Ci. 282-421) The present invention relates to apparatus, and a method for oven heat distribution in a coke oven gas underfired coke oven battery to produce foundry coke.

More specifically, the present invention contemplates the modification of the oven heat distribution in a conventional cross-regenerative horizontal coke oven battery of the type of H. Koppers U.S. Patent 1,051,372 which is primarily designed to produce blast furnace or domestic coke, by structurally modifying and Operating the battery in such a different manner to obtain a "top-firing, as well as an under-firing, of the ovens with coke oven gas in order to effect a more uniform oven heat distribution from top to bottom of the coal masses in the coking chambers to satisfactorily produce a premium foundry coke.

In recent years there has been an increasing demand tor premium foundry coke on blast furnace coke producers by foundrymen requiring premium foundry coke. It generally has been agreed among foundrymen that such foundry coke should be of a type that has the ability to better support a charge in a cupola for the manufacture of iron for castings, that has uniformity of size, that has sufficient greater toughness to minimize degradation resulting in partially undersized coke which would otherwise occur in handling the coke when it has reached the foundry, and that has uniformity from car to car.

In attempting to satisfy the increasing demands for this premium foundry coke and to meet the requirements specified by foundrymen, the producers of high quality foundry coke have heretofore been faced with many problems, since to design and construct special coke oven batteries primarily designed to produce foundry coke of quantity and quality satisfactory to meet the demands and specification of foundrymen would not only be time consuming, but would involve costs completely out of proportion to the profits to be realized and would be a prohibitive solution of present problems. On the other hand, the use of the many existing horizontal coke ovens, which were primarily designed for the production of blast turnace and domestic coke, to produce premium foundry coke also would entail certain like problems in the absence of some simple modification.

One of the different factors involved in producing the desired premium foundry coke in these ovens designed primarily for producng blast furnace or domestic coke is the coking time required. This foundry coking time is longer than that for producing blast furnace or domestic coke. But, merely lengthening the coking time in the conventional horizontal coke oven that utilizes coke oven gases for underfiring does not, in itself, produce a premium foundry coke of the quality desired, since the lengthening in coking time introduces another factor of a diferent substantial temperature gradient between the bottom and top of a coking chamber. In view of this ternperature gradient from bottom to top of each heating fine, the fiame heating of the top region of the coking chamber for a longer time selected to produce from the coal in that level of the coking chamber the desired premium foundry coke would result in an overheating of the coking chamber at the bottom region by fiame initiated there. On the other hand, the flame heating of the bottom region of the coking chamber when restricted for a Well as the lower horizontal fiues.

selected longer coking time to produce premium foundry coke would result in an underheating of the coking chamber at the top region and a black top" would exist upon completion of the coking period. To solve this problem and yet maintain the longer coking time required by fiame heating from below to top, it is essential that uniform oven heat distribution -be maintained from bottom to top of the coking chambers. One way to obtain a substantial uniformity of heating would be to introduce a diluent such as producer gas into the underfiring coke oven gas. However, the special manufacture of such a diluent for the sole purpose of making `foundry coke is prohibitive. .For example, if producer gas is to -be used as a diluent for coke oven gas, the same operational costs exist for Operating the producer gas apparatus at a lower rate sufficient to supply the demands for dilution of coke oven gas tor firing of the coke oven battery as would exist if the apparatus were operated at a higher rate to satisfy other demands, which demands might not always be present at the time of demand for producer gas as a diluent for firing the coke oven batteries with coke oven gas in manufacture of foundry coke.

In order to utilize the existing horizontal coke oven batteries of the aforesaid type to make quality premium foundry coke, an improvement in the structure of these batteries and the method of Operating the same has now been developed. This improvement provides the features necessary for efiicient operation and eliminates disadvantages of the previous systems heretofore mentioned.

The present invention teaches an eficient and inexpensive Way of modifying the existing conventional horizontal coke oven batteries of the type of said Patent l,051,372 by the removal of any obstructions that might presently exist in upper horizontal fiues superposed above the lower horizontal fiues communicably connecting the single divided Vertical flue groups disposed in end-to-end relationship in the heating Walls of the batteries. This makes a complete passage out of the upper horizontal flues and renders the Vertical fine groups communicable with each other through these upper horizontal ues as The invention further provides a single top firing means in communication with these horizontal flues solely at the middle vertical plane between the extremities of abutting end to end groups of flues operable in alternation with each other 'for upfiow combustion in each fine of a group and downow of combustion products in each fiue of a group to introduce heating gases, preferably rich coke oven gases at these selected regions in the battery to provide uniform oven heat distribution 'for producng premium foundry coke as distinguished from ordinary oundry coke. The invention avoids the disadvantages of the system as previously used and provides an economical structure and method of operation that permts a more uniform oven heating distribution in the manufacture of premium foundry coke at the same, if not an increased, rate of production.

Still another feature of the invention is the method of Operating an otherwise conventionally underfired horizontal coke oven battery of the type of the above noted expired patent to produce premium foundry coke rather than ordinary foundry coke by top firing the battery in controlled relationship with the unchanged underfiring through the converted upper horizontal fine, which was an otherwise normally cool top horizontal flue in order, to obtain a uniform heat distribution from the bottom to the top ot the coking chambers in making toundry coke.

Another feature of the invention is the Simplicity of means for this type of conventional horizontal coke oven battery to readily permit this conventional battery to be converted inexpensively from a producer of blast furnace and domestic coke to a producer of premium foundry coke.

A particular advantage of the invention is that the means so provided permits part of conventional underfired horizontal coke oven battery of the type specified to be used inexpensively and readily for the production of blast furnaces and domestic coke and another part to be used for the production of the new premium foundry coke. This provides greater ftexibility ir the operation of the battery.

The invention cornprises a coke oven battery including a plurality of horizontal coking chambers; a plurality of heating walls contiguous thereto; vertical combustion flue groups disposed in each of said heating walls in end-toend relationship; regenerators located at a level lower than said flue groups, each of said regenerators communicating with a flue group and adapted to be operated in alternation with one of the other regenerators connected to another flue group to take up the waste heat of the outfloW gases and impart it on reversal to the inflow air; upper and lower horizontal flues disposed in the upper portion of each of said heating walls one alongside the top-most part of the coking chambers and one at lower level, each of said horizontal flues communicably connecting the Vertical flues of at least two abutting end to end groups in the wall in which it is positioned so that gases may flow between said connected vertical fiue groups in alternating direction; top firing gas discharge means positioned so that all of said top firing gases are discharged into each of said upper horizontal flues in the region of the middle vertical plane between the opposite extremities of the abutting end to end groups alternating vertical combustion flue groups so that top firing gases introduced in said horizontal flues will fiow in alternating direction in accordance With the alternating direction of flow of gases in the connected vertical combustion flue groups.

It is obvious that various changes can be made by one skilled in the art in the arrangement, form, Construction and type of the various elements disclosed without departure from the scope or spirit of this invention. Thus, for example, top firing" gas discharge apparatus may be communicably connected with the top or upper horizontal flues at the opposite end regions as well as solely substantially =at the center as is disclosed in the drawings. Furthermore, it is a feature of this invention to provide a flue structure design in the heating walls of the coke oven battery of the expired patent type referred to that will insure uniform heating of the top regions of the coking chambers as Well as the lower regions.

References will now be made to the accompanying drawings which illustrate and exemplify an embodirnent of an apparatus of the invention in a preferred type of Construction.

FIGURE 1 is a vertical sectional elevation taken longtudinally of a conventional horizontal coke oven battery of the type of said Patent 1,0S1,372 without modification, part being in the plane indicated by E-E in FIGURE 2 and part being in the plane indicated by F-F in FIG- URE 3.

FIGURE 2 is a vertical section of a coking chamber and the regenerators therebelow taken in a plane indicated by A-A in FIGURE 1.

FIGURE 3 is a vertical section taken longitudinally of the heating wall, part being in the plane indicated by B-*B and part being in the plane indicated by C- C of FIGURE 1.

FIGURE 4 is a view of a portion of the heating wall shown in FIGURE 3 as modified for the simple single top-firing operation uninterrupted top or upper horizontal flue and showing the sliding bricks in the top horizontal flue in the modified open position.

FIGURE S is a View of a portion of the battery as in FIG. 4 showing the simple modification for top firing,

CJI

the View being taken longitndinally of the battery from the coke side.

FIGURE 6 is an enlarged view of a portion of FIG- URE 5.

FIGURE 7 is a top View of the top firing apparatus as disclosed in FIGURES 4-6.

Referring to the drawings, chanbers 2 and 4` are crossregenerators adapted to be operated in alternation and are divided by wall 5 and built on the customary foundation 6 as in H. Koppers US. Patent No. 1,05l,372 of 1913. Each regenerator communicates through -a sole channel outlet 8 with a stack flue system (not shown) as is conventional in the art. Surmounting the regenerators 2, 4 are horizontal coking chambers lt) and heating walls 12 of which any desired number may be provided. Each coking chamber l@ is between walls 12, each wall containing a longitudinal series of vertical heating ues 14 forming abutting end-to-end groups of combustion flues rising from a base and each containing an upward rich gas nozzle 16, one at the bottom of each flue; and each flue contains a pair of short air regenerator inlet ports 18, as indicated in section C-C of FIGURE 3 and section EE of FIGURE 1 to either side and rising above the nozzles 16. These ports feed the heated air rising from the regenerators and mix it in the flues at an elevation above the respective nozzles 16 with the rich gas that is introduced into the flues. Each row of flues 14 has eX- tending underneath it, a gas passage 20 from which the nozzles 16 are fed, this passage being provided at each end With element 22, known in the art as a gas gun.

As is disclosed in said Patent 1,05 1,372 as normally built and operated, this type of oven has, as shown in FIGURE 3, the row of flues 14- in each heating wall discharge at their upper ends into a lower top horizontal flue 24- in a superstructure containing auxiliary upper top horizontal cooling ues 26. Each of the horizontal flues 26 has a dividing brick 50 midway the ends preventing reverse flow of gas therethrough and communicates with the normal horizontal flue 24 below it through access openings 28. Positioned above each vertical flue 14 of the vertical flue groups are the sliding bricks 39 for these combustion flues and above each opening 28, the sliding bricks 32. The sliding bricks 30 and 32 are moved away from their respective openings when any of the heating walls of the battery is to be used for making premium foundry coke in the practice of this invention. When the heating walls of the battery are to be used for the production of blast furnace or domestic coke, then the sliding bricks 32 are moved over the openings 28 to cut oil? the communication of the upper top auxiliary lower top horizontal flues 26 with the horizontal flues 24-, the auXiliary upper horizontal flues 26 then act as cooling flues for the top-most parts of the coking charnbers. Extending upwardly from the passage 26 and aligned with openings 28 are the cap covered access flues 34 for manipulation of the bricks.

The rich gas for heating the ovens can be derived from the oven chambers 10 themselves and fed back to the vertical flue group in the heating walls through the mains 36, 36 extending along opposite sides of the battery. These rich gas mains are opened alternately to the gas guns 22 leading to the opposite ends of the passages 20; Each time a main on one side is open, communication of the main on the opposite side with the guns on that side is closed.

In operation, gas, which for the purposes of this invention preferably is coke oven gas derived from the ovens, enters the passages 20 in the left half of each heating wall 5 by way of the main 36 and guns 22 on one side of the battery. The gas discharges through the nozzles 16 into the vertical combustion flues 14 in that half of the heating wall. Combustion air enters the previously heated regenerator chambers 2 and passes through the regenerator ports 18 for mixture With the rich gas in said half of the flues. The burning fuel mixture n'ses through the flues 14 above the regenerator chambers 2 and passes horizontally through horizontal flues 24 and thence down -the flues 14- above the other set of regenerator chambers 4 on the opposite right half side of the Wall 5 into the regenerator chambers 4 thereof, to heat the latter. The gases of combustion then pass through the waste heat sole fine system and smolrestack (not shown). As will be understood, by closing the main 36 on this left side and at the same time opening the main 36 on the opposite right hand side, the operation is reversed. The vertical flues in the right hand half then operate for upflow combustion and the vertical flues in the left hand half then operate concurrently to simultaueously eXhaust the waste gases to the regenerators 2.

The Construction and operation of the disclosed conventional horizontal battery, as thus far described, are well known in the art as those of the aforesaid Patent 1,05l,372 and do not require more detailed description herein.

FIGURES 4-7 disclose the portion of the conventional horizontal battery of FIGURES 1-3 as modified according to this invention with a top firing apparatus making the battery operable for the improved production of premium foundry coke. As is shown in FIGURES 4 and 5, a main 38, which may vary in design but is preferably an 8 inch steel pipe, runs longitudinally over the top of the battery, being supported thereon in the middle vertical plane thereof by supports 40 The main 33 is connected to the same rich gas source (not shown) as is main 36, 36 so that such gas may be introduced into the top of the battery for top firing as is above set forth and hereinafter described. communicably connected with the main 38 at longitudinal intervals spaced in accordance with the spacing of the heating walls longitudinally in the battery are gas off-takes 4-2. Each of these off-takes includes a gas cock 44 and a nozzle 46 for the controlled discharge of top firing gases into the top of the coke oven battery. Each of the nozzles 46 is introduced solely into a selected single one of the access flues 34 of each heating wall 2, each extending above each heating fiue in the several heating walls that is at the middle. vertical plane between the two opposite end flues of the abutting end to end flue groups in a said heating wall, which access flues are communicably connected with the upper top horizontal flues 26. As aforestated, these upper top horizontal flues were formerly used only for cooling. lt is preferred that each nozzle 46 be introduced into an access fine 34 at a region above the point of reversal of the waste gas in the lower top horizontal flue 24. Specially designed slotted plates 48 which fit snugly around the nozzle are used to replace the inspection caps in the access flues 3 1 that are selected to be adapted with the top firing gas discharge means. The nozzles 46 may be of any length desired and of any size but it is preferable that their ends be approxirnately 18 inches above the upper top auxiliary horizontal flues 26 in order to prevent them from deteriorating too rapidly, and that they be of l inch standard steel pipe.

In the modified oven, as disclosed in FIGURES 4-7 of the drawings, the dividing bricks 50 in the upper top auxiliary horizontal flues 26 are. removed, as indicated by the broken lines in FIGURE 4. The removal of these bricks 5@ together with removing bricks 32 from above the flues 28 allows the upper flues 26 which were normally upper top horizontal cooling flues to operate as auxiliary upper top horizontal firing heating flues in the production ot premium foundry coke. This further assures the uniformity of heat distribution in the coke oven battery, since these flues are positioned at the topmost regions of the coking chambers 10, as shown in FIG. 1. Although holes may be drilled through the bricks 50, a simpler and more efcient system is obtained by entirely removing these bricks.

In the operation of the coke oven battery for the production of premium foundry coke sliding bricks 32 are slid away from the openings 28, thus rendering each of the upper top auxiliary horizontal flues 26 communicable with the lower top horizontal flue 24 below it. The sliding bricks 30 are also slid away from the: tops of each of the vertical flues 14 so as to be positioned in a similar manner to that for throttling the gas flow when the battery is used for production of blast furnace or domestic coke, but are throttled somewhat moreso for less intense heating and longer coking time. The coke oven battery is underfired substantially as aforedescribed but for a longer period of time and at a lower temperature than used in production of blast furnace or domestic coke. simultaneously, top firing" of the battery is carried on by introducng rich coke oven gas which is derived from the charges being carbonized into the main 38 and discharging it into the mid-region of the upper top auxiliary horizontal flues 26 through the gas ofitakes 4 2. The top firing temperature is controlled throughout the total underfiring time to insure a more uniform heat distribution. Since the gas is introduced solely in a region near middle vertical plane between alternating vertical flue groups in a heating wall, the top firing gas will flow in alternating direction in accordance with the alternating direction of flow of the underfiring gas through the vertical ue groups. The modification of the conventional horizontal coke oven of FIGURES 1-3 with the top firing gas discharge means as disclosed in FIGURES 4-7 provides for a controlled uniform oven heat distribution and coking of the upper portions of the coking chamber while retaining the prior upflow combustion in all the vertical flues in each heating wall from their bases upwardly as heretofore in said patent when operating such an oven battery for the production of premium foundry coke and permits the battery to be run for longer periods of time at lower temperatures, than is possible in the production of blast furnace and domestic coke without dangerous overheating near the top of the coke oven battery. The battery walls may be readly converted back for blast furnace coke production merely by disconnecting the gas supply to the main 38, `and readjusting the sliding bricks 30, 32, and turning on more gas.

While the description and drawings illustrate particular embodiments of the invention, various modifications within the language of the specification and claims are intended to be claimed heren.

The invention claimed is:

1. A horizontal coke oven battery comprising a series of alternate horizontal coking charnbers and intermediate heating walls arranged side by side in a row, each of said heating walls being constituted of abutting end to end groups of vertical combustion flues, horizontal flues disposed along the tops of the abutting end to end groups of flues in said heating walls for flow of waste gas along the tops of the flues in alternation from one group to the other of the abutting end to end groups in each heating wall; two sets of regenerators below the coking chambers and heating walls and operable in alternation with each other for concurrent inflow pre-heating of combustion media in one set during simultaneous outow of the waste gases of combustion through the other set, the regenerators of one set being communicably connected at their tops with the bottoms of each of the vertical flues of each of one of the groups that abut the other group of vertical combustion flues in the heating walls while the regenerators of the other set being likewise communicably connected with each of the vertical flues of each of the other of the groups of vertical combustion flues that said one of the groups of Vertical flues abut in the heating walls for concurrent upflow of combustion in each vertical fine of each group in a heating wall in alternation with off-flow of the waste gas through the horizontal flues at their tops to and down through an abutting group of vertical flues in the same heating wall in alternation With each other; a top firing gas discharge burner so positioned between the two opposite end vertical flues or" abutting flue groups in the same heating wall as to -be solely at the region of the middle vertical plane between the abutting alternating end to end flue groups in the same heating wall, so that all top firing gases discharged intermediate the extremities of a horizontal flue connecting said groups are discharged in the horizontal flues solely in the region of the middle vertical plane between the abutting alternating Vertical flue groups with flow of the top firing gases in alternating direction from the same single top firing gas discharge. burner along the horizontal flue in the direction of downflow of waste gas through the groups of flues when operable for downfloW of waste gases in accordance With the alternate reversal in direction of flow of gas through the flue groups upon reversal of the regenerators, and which includes an upper auxliary horizontal flue disposed in each heating Wall above the horizontal flues therein along the tops of the abutting alternating flue groups therein, at an elevation alongside the top-most region of the coking chamber contiguous to the heating walls, with the upper auxiliary flue communicating by ducts above the respective Vertical flues with the horizontal flue below it, and in which said gas discharge burner is so positioned that all of said top firing gases are discharged first into upper auxiliary horizontal flue so that top firing gases will flow in alternating direction alongside the top-most part of the adjacent oven chambers into the lower horizontal flue before flowing down through the group of vertical flues operable for downflow of waste gases to the regenerators during the concurrent upflow combustion heating of the Vertical combustion flues of an abutting group then operable for upflow combustion alongside the coking chambers.

2. A horizontal coke ove-n battery, as claimed in claim 1, and in which 'the vertical flues in each row in each heating wall are single divided into two abutting end to end flue groups as aforesaid at the middle length of the heating wall.

3. A method of operation to produce premium foundry coke from coal in a horizontal coke oven battery having coking chambers alternating in position side by side with heating walls therefor each constituted of abutting end to end alternating groups of vertical combustion flues communicably connected with each other at their tops by `a horizontal flue for flow of waste gas from each group to the other of the abutting alternating end to end groups, and crosswise regenerators communicating with each of the abutting end to end groups in each heating wall at their lower parts for alternate inflow of preheated medium to each group in alternation with outflow of waste. gas from an abutting group of heating flues in each Wall, said method comprising the steps of underfiring each group in alternation with the other of an abutting end to end group in each heating wall by upflow combustion with a mixture of rich fuel gas unpreheated by said regenerators and air preheated by said regenerators introduced at the lower parts of the combustion flues while simultaneously top-firing the tops of the heating walls by continuously and uninterruptedly introducing unpreheated rich gas at a single region for flow into said horizontal flues solely at the middle vertical plane between the extremities of the abutting end to end groups of a heating Wall With flow of such rich gas crosswise of the battery along the top parts of the horizontal flues above first one group and then the other group of flues in alternation in accordance with the direction of flow of waste gas from a group operable for upflow to the group then operable for downflow of waste gas from the flue group operable tor upflow combustion in accordance with the alternating direction of flow of waste gas as a result of the reversal of the regenerators, and in which the top firing gas is first introduced to a horizontal flue at an elevation alongside the top-most part of the coking chambers adjacent the heating wall before the top firing gas passes to the horizontal flue parts along the tops of the abutting flue groups.

4. A method as claimed in claim 3, and in which all the flues in each so top fired heating wall `are underfired as aforesaid as two groups single divided at the middle length of the heating wall so that all flues of each half of the wall on each side. of the aforesaid middle vertical plane thereof operate concurrently for upflow in alternation, for upflow combustion simultaneously with downflow of the waste gases of combustion therefrom in all the flues of the other half of the wall on the other side of said middle vertical plane of the wall.

References Cited in the file of this patent UNITED STATES PATENTS 663,638 Poetter Dec. 11, 1900 898,439 Collins Sept. 15, 1908 958,154 Mueller May 17, 1910 1,051,372 Koppers Jan. 21, 1913 1,193,066` Roberts Aug. 1, 1916 1,292,369 Plantinga Jan. 21, 1919 1,410,784 Van Ackeren Mar. 28, 1922 l,445,552 Piette Feb'. 13, 1923 1,469,491 Van Ackeren Oct. 2, 1923 1,775,191 Coppee Sept. 9, 1930 1,775,l92 Coppee Sept. 9, 1930 1,873,077 Van Ackeren Aug. 23, 1932 2,306,678 Van Ackeren Dec. 29, 1942 2,378,450 Van Ackeren June 19, 1945 FOREIGN PATENTS 23,562 Great Britain Mar. 7, 1912 (1911) 

3. A METHOD OF OPERATION TO PRODUCE PREMIUM FOUNDRY COKE FROM COAL IN A HORIZONTAL COKE OVEN BATTERY HAVING COKING CHAMBERS ALTERNATING IN POSITION SIDE BY SIDE WITH HEATING WALLS THEREFOR EACH CONSTITUTED OF ABUTTING END TO END ALTERNATING GROUPS OF VERTICAL COMBUSTION FLUES COMMUNICABLY CONNECTED WITH EACH OTHER AT THEIR TOPS BY A HORIZONTAL FLUE FOR FLOW OF WASTE GAS FROM EACH GROUP TO THE OTHER OF THE ABUTTING ALTERNATING END TO END GROUPS AND CROSSWISE REGENERATORS COMMUNICATING WITH EACH OF THE ABUTTING END TO END GROUPS IN EACH HEATING WALL AT THEIR LOWER PARTS FOR ALTERNATE INFLOW OF PREHEATED MEDIUM TO EACH GROUP IN ALTERNATION WITH OUTFLOW OF WASTE GAS FROM AN ABUTTING GROUP OF HEATING FLUES IN EACH WALL, SAID METHOD COMPRISING THE STEPS OF UNDERFIRING EACH GROUP IN ALTERNATION WITH THE OTHER OF AN ABUTTING END TO END GROUP IN EACH HEATING WALL BY OUTFLOW COMBUSTION WITH A MIXTURE OF RICH FUEL GAS UNPREHEATED BY SAID REGENERATORS AND AIR PREHEATED BY SAID REGENERATORS INTRODUCED AT THE LOWER PARTS OF THE COMBUSTION FLUES WHILE SIMULTANEOUSLY TOP-FIRING THE TOPS OF THE HEATING WALLS BY CONTINUOUSLY AND UNINTERRUPTEDLY INTRODUCTING UNPREHEATED RICH GAS AT A SINGLE REGION FOR FLOW INTO SAID HORIZONTAL FLUES SOLELY AT THE MIDDLE VERTICAL PLANE BETWEEN THE EXTREMITIES OF THE ABUTTING END TO END GROUPS OF A HEATING WALL WITH FLOW OF SUCH RICH GAS CROSSWISE OF THE BATTERY ALONG THE TOP PARTS OF THE HORIZONTAL FLUES ABOVE FIRST ONE GROUP AND THEN THE OTHER GROUP OF FLUES IN ALTERNATION IN ACCORDANCE WITH THE DIRECTION OF FLOW OF WASTE GAS FROM A GROUP OPERABLE FOR UPFLOW TO THE GROUP THEN OPERABLE FOR DOWNFLOW OF WASTE GAS FROM THE FLUE GROUP OPERABLE FOR UPFLOW COMBUSTION IN ACCORDANCE WITH THE ALTERNATING DIRECTION OF FLOW OF WASTE GAS AS A RESULT OF THE REVERSAL OF THE REGENERATORS, AND IN WHICH THE TOP FIRING GAS IN FIST INTRODUCED TO A HORIZONTAL FLUE AT AN ELEVATIN ALONGSIDE THE TOP-MOST PART OF THE COKING CHAMBERS ADJACENT THE HEATING WALL BEFORE THE TOP FIRING GAS PASSES TO THE HORIZONTAL FLUE PARTS ALONG THE TOPS OF THE ABUTTING FLUE GROUPS. 